The present invention relates to the general field of thrust reversers for bypass turbojets. It relates more particularly to an electromechanical thrust reverser having at least two displaceable elements which co-operate, when the reverser is in its open position, in producing thrust reversal, such as, for example, a thrust reverser having doors, grids, or shells.
Thrust reversers fitted to bypass turbojets are well known in the field of aviation. They serve to increase aircraft safety by assisting in braking during landing. Thrust reversers are generally in the form of at least two moving elements, such as sliding doors, which are suitable for being moved relative to the pod of the turbojet by control actuators so that when operating in thrust reversal, i.e. when in the open position, they constitute an obstacle for a fraction of the gas coming from the turbojet, which fraction is diverted forwards so as to deliver reverse thrust to the airplane.
The sliding doors are generally moved by a hydraulic control system. Such a control system essentially comprises hydraulic actuators for driving the doors of the reverser, a hydraulic control unit for feeding the chambers of the control actuators with hydraulic fluid under pressure, and hydraulic circuits. The hydraulic power needed for feeding that type of control system is taken directly from the hydraulic circuit of the airplane.
While the reverser is being opened and closed, it is essential for the doors to be displaced in synchronized manner. Non-synchronized displacement of the doors generates high levels of dynamic stress on the reverser and can cause large amounts of damage to the reverser and the turbojet. Poor synchronization of door displacement results from different loadings on the doors, leading to a large difference in position between them. Furthermore, it is possible that the driving forces applied to the doors of the reverser are different. Under such circumstances, risks can arise of the reverser being distorted and thus damaged.
In order to detect any such variation in the forces exerted on a hydraulically-controlled thrust reverser and in order to detect any difference between the forces on the doors thereof, it is known to provide the control actuators with sensors measuring the pressure of the hydraulic fluid present in the chamber of the actuators. By comparing the pressure measurements taken by the various sensors, it is possible to detect both any variation in the forces exerted on the reverser, and any force difference between the doors, thus making it possible to avoid any twisting of the reverser, which would lead to a difference in position between the doors.
Thrust reverser technology using a hydraulic control system presents drawbacks associated in particular with the volume occupied by the various hydraulic circuits. Finding a path for these circuits is difficult because of the small amount of space that is available on the front frame of the reverser. Another drawback of this technology lies in using a hydraulic fluid that is dangerous since it is corrosive and flammable. In addition, the use of pressure sensors for detecting and remedying any blocking or jamming of the doors makes it impossible to be aware of how the performance of the thrust reverser is varying over time in order to be able to anticipate any degradation and/or aging thereof.